Enable type-checking in src

.eslintrc

@@ -2,5 +2,8 @@
   "extends": "babel",
   "env": {
     "node": true
+  },
+  "rules": {
+    "indent": 0
   }
 }

.flowconfig

@@ -2,12 +2,20 @@
 .*/lib/.*
 .*/test/.*
 .*/build/.*
+.*/node_modules/.*
+.*/rollup.config.js
+.*/bin/.*
+.*/scripts/.*
 
 [include]
 
 [libs]
 
 [options]
+all=true
 strip_root=true
 suppress_comment= \\(.\\|\n\\)*\\$FlowFixMe
 suppress_comment= \\(.\\|\n\\)*\\$FlowIssue
+suppress_comment= \\(.\\|\n\\)*\\$FlowIgnore
+suppress_comment= \\(.\\|\n\\)*\\$FlowNonNull
+suppress_comment= \\(.\\|\n\\)*\\$FlowCast

src/index.js

@@ -1,3 +1,4 @@
+import type { Options } from "./options";
 import Parser, { plugins } from "./parser";
 import "./parser/util";
 import "./parser/statement";
@@ -11,18 +12,20 @@ import { types as tokTypes } from "./tokenizer/types";
 import "./tokenizer";
 import "./tokenizer/context";
 
+import * as N from "./types";
+
 import estreePlugin from "./plugins/estree";
 import flowPlugin from "./plugins/flow";
 import jsxPlugin from "./plugins/jsx";
 plugins.estree = estreePlugin;
 plugins.flow = flowPlugin;
 plugins.jsx = jsxPlugin;
 
-export function parse(input, options) {
+export function parse(input: string, options: Options): N.File {
   return new Parser(options, input).parse();
 }
 
-export function parseExpression(input, options) {
+export function parseExpression(input: string, options: Options): N.Expression {
   const parser = new Parser(options, input);
   if (parser.options.strictMode) {
     parser.state.strict = true;

src/options.js

@@ -1,17 +1,19 @@
 // A second optional argument can be given to further configure
 // the parser process. These options are recognized:
 
-export const defaultOptions: {
-  sourceType: string,
-  sourceFilename: any,
-  startLine: number,
-  allowReturnOutsideFunction: boolean,
-  allowImportExportEverywhere: boolean,
-  allowSuperOutsideMethod: boolean,
-  plugins: Array<string>,
-  strictMode: any,
-  ranges: boolean,
-} = {
+export type Options = {
+  sourceType: "script" | "module";
+  sourceFilename?: string;
+  startLine: number;
+  allowReturnOutsideFunction: boolean;
+  allowImportExportEverywhere: boolean;
+  allowSuperOutsideMethod: boolean;
+  plugins: $ReadOnlyArray<string>;
+  strictMode: ?boolean;
+  ranges: boolean;
+};
+
+export const defaultOptions: Options = {
   // Source type ("script" or "module") for different semantics
   sourceType: "script",
   // Source filename.
@@ -44,10 +46,11 @@ export const defaultOptions: {
 
 // Interpret and default an options object
 
-export function getOptions(opts?: Object): Object {
+export function getOptions(opts?: Options): Options {
   const options = {};
   for (const key in defaultOptions) {
     options[key] = opts && key in opts ? opts[key] : defaultOptions[key];
   }
+  // $FlowIgnore
   return options;
 }

src/parser/comments.js

@@ -25,20 +25,20 @@
  */
 
 import Parser from "./index";
+import * as N from "../types";
 
-function last(stack) {
+function last<T>(stack: $ReadOnlyArray<T>): T {
   return stack[stack.length - 1];
 }
 
-const pp = Parser.prototype;
-
-pp.addComment = function (comment) {
+Parser.mixin(class extends Parser {
+addComment(comment: N.Comment): void {
   if (this.filename) comment.loc.filename = this.filename;
   this.state.trailingComments.push(comment);
   this.state.leadingComments.push(comment);
-};
+}
 
-pp.processComment = function (node) {
+processComment(node: N.Node): void {
   if (node.type === "Program" && node.body.length > 0) return;
 
   const stack = this.state.commentStack;
@@ -128,10 +128,8 @@ pp.processComment = function (node) {
       // that comes after the node. Keep in mind that this could
       // result in an empty array, and if so, the array must be
       // deleted.
-      node.leadingComments = this.state.leadingComments.slice(0, i);
-      if ((node.leadingComments: Array<any>).length === 0) {
-        node.leadingComments = null;
-      }
+      const leadingComments = this.state.leadingComments.slice(0, i);
+      node.leadingComments = leadingComments.length === 0 ? null : leadingComments;
 
       // Similarly, trailing comments are attached later. The variable
       // must be reset to null if there are no trailing comments.
@@ -153,4 +151,5 @@ pp.processComment = function (node) {
   }
 
   stack.push(node);
-};
+}
+});